The biochemical and biophysical properties of developing skeletal and dental tissue constituents are being studied by several techniques. Dentin, bone and enamel proteins are also being investigated as to their dynamic and structural influences on crystal formation in biological systems. Special emphasis is placed on phosphoprotein biochemistry in these hard tissue matrix studies. BIBLIOGRAPHIC REFERENCES: R.A. Peckauskas, J.D. Termine and I. Pullman, "ESR Investigation of the Binding of Acidic Biopolymers to Synthetic Apatite". Biopolymers, 15, 569-581, 1976. R.A. Peckauskas, I. Pullman and J.D. Termine, "ESR Investigation of the Binding of Some Neutral Polyamino Acids to Synthetic Apatite". Biopolymers 16, 199-206, 1977.